Purge new localstorage memory cache when under memory pressure.

content/browser/dom_storage/local_storage_context_mojo.cc

Index: content/browser/dom_storage/local_storage_context_mojo.cc
diff --git a/content/browser/dom_storage/local_storage_context_mojo.cc b/content/browser/dom_storage/local_storage_context_mojo.cc
index 6437963aa23a92dc79719816abeecb18bb79a33c..0469ec7e4db2a14d5507b54d4b6328dd2b7a769b 100644
--- a/content/browser/dom_storage/local_storage_context_mojo.cc
+++ b/content/browser/dom_storage/local_storage_context_mojo.cc
@@ -280,6 +280,11 @@ void LocalStorageContextMojo::Flush() {
     it.second->level_db_wrapper()->ScheduleImmediateCommit();
 }
 
+void LocalStorageContextMojo::PurgeMemory() {
+  for (const auto& it : level_db_wrappers_)
+    it.second->level_db_wrapper()->PurgeMemory();
+}
+
 leveldb::mojom::LevelDBDatabaseAssociatedRequest
 LocalStorageContextMojo::DatabaseRequestForTesting() {
   DCHECK_EQ(connection_state_, NO_CONNECTION);